Internal combustion engine



y 1941. K. L. HERRMANN 2,243,820

- INTERNAL COMBUSTION ENGINE Filed Sept. 25, 1940 2 Sheets-Sheet l rINVENTOR- j-Z 1, Herr/yarn;

' May 27, 1941. K. L. HERRMANN 2,243,820

INTERNAL COMBUSTION ENGINE Filed Sept. 25, 1940 2 Sheets-Sheet 2Patented May 27, 1941 UNITED STATES PATENT OFFICE INTERNAL COMBUSTIONENGINE Karl L. Herrmann, South Bend, Ind. Application September 25,1940,Serial No. 358,240

7 Claims.

This invention relates 'to internal combustion engines and particularlyto those of the barrel type, the principal object being the provision ofa new and novel form of connection between the pistons and the cam whichwill reduce the amount of wear heretofore occurring at this point,

The invention relates to what is commonly known as a barrel type ofengine, that is an engine in which the cylinders are arranged with theiraxes parallel to the shaft and equally angularly arranged about theshaft and with such axes lying in acylindrical surface concentric withthe axis of the shaft. The cylinders are arranged in two groups, onegroup at each end of the engine and each cylinder of each group is inopposed relation to a corresponding cylinder of the other group and witha double ended piston associated with each opposed pair of cylinders,the shaft being provided with an axial cam received by the centralportion of the pistons and rollers being interposed between the oppositefaces of the cam and the pistons to transmit the thrust between thepistons and the cam.

Objects of the invention include, in an engine of the type described, aroller construction which will take care of any mis-alignment betweenthe rollers and the cam faces and yet will distribute the wear betweenthe rollers and the cam over a desired width of face of the cam; theprovision, in an engine of the type described, of a roller constructionwhich will have substantially point contact with the cam but in whichthe line of contact between some rollers and the cam will be in a circlehaving a diiferent radius from the line of contact of other rollers withthe cam; theproof the crown on certain of the rollers occurring 40 thanthe high points of the crown on other rollers;

at a different distance radially ,of the engine shaft and the provisionof an engine of. the type described in which the various rollersinterposed between the cam and the pistons are crowned with the highpoints of the crowns of the various rollers arranged at variouspositions axially of the rollers whereby the points of contact ofcertain of the rollers with the cam occurs at a different radialdistance from the center of the engine shaft than the point of contactof other of the rollers with the cam.

The above being among the objects of the present invention, the sameconsists in certain novel features of construction and combinations ofParts to be hereinafter described with reference to the accompanyingdrawings, and then claimed, having the above and other objects in view.

I In the accompanying drawings which illustrate a suitable embodiment ofthe present invention and in which like numerals refer to like partsFig. 3 is a transverse sectional view of the piston taken on the line3'-3 of Fig. 2;

Fig. 4 is a fragmentary transverse sectional view taken on the line 4-4of Fig. 1 and illustrating the arrangement of the cylinders; and,

Figs. 5, 6 and 7 are enlarged fragmentary, sectional views taken on thelines 5-5, 6-6 and 1-4, respectively, of Fig. 4 and illustrating theconstruction and arrangement of the rollers interposed between thepistons and the cam.

The present invention relates to a barrel type engine. As is wellunderstood in the art these engines comprise a rotating shaft aboutwhich is grouped a plurality of equally angularly spaced cylindersarranged with their axes lying in the surface of a cylinder concentricwith the shaft. The cylinders in the present case, and as is usual, arearranged in two groups, one at each end of the engine with their openends opposed to each other and each cylinder of one group in alignmentwith one cylinder of the opposite group.

' Each opposed pair of cylinders receives therein a double ended piston,and a cam fixed to the rotating shaft is received within or by thecentral portion of each piston. Usually, and as in the case of thepresent invention, the pistons support rollers which engage the oppositefaces of the cam so as to reduce the friction between the piston and thecam when the thrust of the pistons under explosions in the cylinders isexerted upon the cam to induce a rotational effect thereon.

While the present invention is applicable to any satisfactory type ofbarrel type engine, it is particularly applicable to the engineconstruction shown, described and claimed in my co-pending applicationfor Letters Patent of the United States for improvements in Internalcombustion engine, filed May 14, 1937' and serially numbered 142,653.Also, while the rollers may be supported in the pistons in any suitablemanner in accordance with the present invention, the preferred method ofsupporting them is that shown and described in my co-pendingapplications for Letters Patent of the United States for improvements inInternal combustion engine, filed October 29, 1938, and seriallynumbered 237,625 and filed May 6, 1940, and serially numbered 333,519,respectively Early experiments with this type of engine illustrated thedifficulty of so accurately machining the various parts that all of therollers between the pistons and the cams, when provided with cylindricalperipheral surfaces, will bear against the cam with true line contact,the surfaces of the complished the results sought to be obtained, thatis eliminating the disadvantages formerly occurring because of a cookedcondition between the rollers and the cam. Further experiments haveindicated, however, that with this crowned construction above described,because all of the rollers are made identical, the wear between therollers and the cam is concentrated upon a substantially narrow circularpath upon the face of the cam and, due to the high pressures existingbetween the rollers and the cams at full engine operation, prematurewearing and breaking down of the cam surface sometimes results, and itis the principal object of the present invention to eliminate thisfurther disadvantage.

This disadvantage is overcome in accordance with the present inventionby employing crowned rollers, but crowning certain of the rollersdifferently from certain other of the rollers. Briefly stated, this isaccomplished by arranging the high point of the crown on one or more ofthe rollers in a diiferent plane axially of the roller than the highpoint of the crown of one or more of the.

other rollers. Theoretically at least all of .the rollers on one side ofthe cam may be arranged with the high point of its crown at a differentaxial position on the roller than the high point of all other rollers onthe same side of the cam, but ordinarily it will not be necessary to goto such extremes inasmuch as it has been found that if the rollers onone side of the cam are provided in two or three groups each havingitscrown high point at a different axial position than the high point ofthe crown of the rollers of the other group or groups, the life of thecam is increased sufficiently for all practical purposes. As will beappreciated by employing such construction the wear on the cam iscutdown, as compared to a similar construction having all'rollerscrowned identically and identically arranged, by the number of groups ofdissimilarly crowned rollers em-- ployed inasmuch as the wear, due tothis new construction, is distributed over the face of the cam in asmany wear circles as there are groups of cams.

cations above referred to and reference to which may be made for greaterdetail of the construction of such engine if desired, As far as thepresent invention is concerned it is sufficient to understand that theengine is provided with a central shaft l0 suitably mounted for rotationwithin a pair of cylinder blocks indicated generally at l2 which arearranged with their ends in axially abutting relationship andsecuredtogether by means of bolts I4. The axially outer ends of thecylinder blocks l2 are each closed by a suitable cylinder head indicatedgenerally at 16 which supports. suitable inlet and/or exhaust valvessuch as l8 controlling the admission of combustible mixture to and theexhaust of burnt gases from the various cylinders of the correspondingblock. Suitable valve actuating mechanism is driven from the shaft ID ateach end of the engine and each is normally enclosed by a housingindicated generally at 20 carried by the corresponding cylinder head Hi.In the particular construction shown by way of illustration eachcylinder block I2 is internally formed to provide six cylinders 22arranged with their axes in the surface of a cylinder concentric withthe axis of the shaft I0 and equally angularly spaced with respect toeach other about the axis of such shaft. The cylinders 22 of onecylinder block l2 are arranged in axial alignment with the correspondingcylinders of the other cylinder block and in each opposed pair of thecylinders 22' a double ended piston indicated generally at 24 isreciprocably received.

A: piston 24 employed in the particular engine shown and which ispreferable, but not necessary to the practices of the present invention,is shown in greater detail in Figs. 2 and 3 from which it will be notedthat it includes opposite end portions 26 integrally connected togetherby means of a ,central strut 28 substantially wholly disposed on oneside of a diametrical plane passing through the axis of, the piston.This strut 2-8 is centrally slotted as at 30, the central axis of theslot lying in a plane including the axis of the piston 24 and theopposite ends of the slot 3|] comprising semi-cylindrical surfacesarranged with their axes perpendicular to the axis of the piston. Acorresponding semi-cylindrical surface 32 is formed on the opposite sideof the piston in alignment with the semi-cylindrical surfaces firstdescribed and the corresponding piston portions 25 are centrallycut-away as at 34 between each aligned pair of semi-cylindricalsurfaces. These semi-cylindrical surfaces form bearing surfaces for thetrunnions of the rollers which themselves are received in correspondingpockets 34 and project outwardly toward one another therefrom.

A cam member 38 is fixed to the shaft lil on line with the joint betweenthe cylinder blocks I2. The cam member 38 is formed with a rim 40 whichis circular in axial, view but the axial faces 42 of which curve axiallyof the shaft In in a simple harmonic curve to provide a cam surface oneach side thereof having two diametrically opposed .axial high pointsthereon. The width ofthe rim MI is such as to be closely receivedbetween the rollers received in the opposed pockets 3! of. each piston24, thus constraining each piston to reciprocate in its correspondingcylindersas the rim l0 passes between its corresponding roller-sand suchrollers acting upon the corresponding faces 42 of the rim 40, under theforce of an explosion'in one of the corresponding cylinders, to impart arotatlonal effect to the cam member 38 and consequently the shaft l0..By employing two axial high points on the cam member 38, it will beappreciated that each piston completes four strokes for each revolutionof the power shaft Hi.

In the broader aspects of the present invention it makes no differencewhether the rollers are formed integrally with their trunnions or not,whether the rollers turn with their trunnions, or whether the trunnionsare fixed in the pistons and the rollers turn on the trunnions. Wherethe semi-cylindrical bearing surfaces for the trunnions are employed asdescribed and shown, the rollers are preferably formed integrally withthe trunnions and one trunnion 50 thus projects from each side of eachroller when the latter is received in the corresponding pocket 34, theone trunnion being received by V the corresponding semi-cylindricalbearing surface 32 and the opposite trunnion being received by thecorresponding semi-cylindrical bearing surface formed at thecorresponding end of the slot 30.

As previously stated, in my second and third co-pending applicationsabove referred to,- the rollers were formed with crowned peripherieswhich, technically at least, therefore, contacted the corresponding camsurfaces 42 in point engagement, and inasmuch as all of the rollers wereidentical and the high point 'of the crown occurred at substantially theidentical axial position on each roller, all of the rollers on each sideof the cam member contacted the corresponding face of the cam along asingle line on such face. While from a practical standpoint despite thefact that theoretically point contact occurs between each of the rollerand the cam, there is suflicient resiliency in the metal of the rollersand the cam to effect a small surface contact between these parts, butnevertheless'the width of this area of contact between the rollers andthe cam surfaces is so limited that when all of the rollers on one sideof the cam contact the cam over such limited width it has been foundthat the surface of the cam, while standing up sufficiently long torender the construction entirely practical, does not stand up for alength of time commensurate with the length of time which other parts ofthe engine stand up in service.

In order to obviate this premature breaking down of the cam surfaces itis the object of the present invention to provide a roller constructionwhich will distribute wear between the rollers and the cam surfaces overan increased width of the cam surfaces. In accomplishing this result thesame general type of crowned rollers as extent as it has been found thatthe wear on the cam will be reduced 'sumciently for all practicalpurposes if two or three different lines of contact between the rollersand their corresponding cam faces is provided instead of the single lineprovided by the former construction, and the labor and time initiallyinvolved in. setting up machinery to produce such a great variety ofcontact lines is largely eliminated and the requirements for carrying arelatively large number of different parts in stock for service ismaterially reduced.

In the broader aspects of the invention the desired result may beobtained in two difierent ways. The first of these is to .make all ofthe rollers identical but to mount them in their pistons at suflicientlydifferent distances from the axis of the power shaft to obtain thedesired result. vSuch a construction, however, requires the pockets 34in the pistons 24, in'the particular piston construction shown by way ofillustration, to be varied in position transversely of the piston toconform to the different positions of the rollers desired, and acorresponding change in any 0 other piston design. This would require asmany different types of pistons in an engine as there are differentlines of contact between the rollers and each cam surface, and,therefore, is not desirable to use for that reason. The second and mostdesirable way to achieve the desired result is to make all of thepistons identical: and vary the position of the high point of the crownon the rollers to provide the desired number of lines of contact betweenthe rollersand the cam faces.-

In other words. the pistons are all identical, and the rollers are allidentical except for the position axially of the rollers at which thehigh point of the crowned surface occurs. This last describedconstruction being preferred, it is illustrated in the drawings.

In the particular construction shown in the drawings the rollers are socrowned as to arrange for three different lines ofcontact between therollers and each face of the cam. This, in view previously employed isemployed, the difference being that the rollers are so constructedand/or ent axial position on the cam than the high point of the crown onother rollers. As will be appreciated, by such a construction one rollerwill contact the cam surface along a line that is at a greater or lesserdistance from the axis of the power shaft of the engine than the line ofcontact between the cam and another roller. It is, of course, possibleto so arrangethe construction that each roller on each side of the camcontacts the corresponding face of the cam along a line on the face ofthe cam different from the line of contact of allother rollers with theface of the cam, and in such case each roller would have a separate lineofcontact between it and the face of the cam. From a practicalstandpoint, however, it is not necessary to go to this I arranged thatthe high point'of the crown of at least certain of the rollers islocated at a differ- I 0 struction.

of the fact that the particular engine shown employs six cylinders ineach of the cylinder blocks, provides a construction whereby not morethan two rollers engage a cam surface along the same line of contactinstead of six as in the older con- It is also noted that while it willusually be desirable that both rollers in the same piston be similarlycrowned and similarly arranged so that their respective lines of contactwith their corresponding cam surfaces will be at the same distance fromthe axis of the power shaft of the engine, this is not necessary as eventhough the rollers in the same piston are crowned at different axialpositions no detrimental effect will result.

In the construction shown in the drawings it is assumed that the rollerson every third piston in each block will be crowned the same andsimilarly arranged, and the construction and arrangement illustrated inFigs. 5, 6 and 7 is illustrative of a preferred arrangement. In otherwords, in the construction illustrated in Fig. 5 the rollers areillustrated at 60a; in Fig. 6 at b,

and in Fig. '7 at 60c. It will be understood that it is assumed in theparticular construction shown. that all of these rollers are integralwith their corresponding trunnions 60, and that the rollers are of anaxial thickness substantially equal to the thickness of the variouspockets 34 in the piston 24 so as to be maintained against substantialaxial movement transversely with respect to its corresponding piston. Itwill also be understood that all of the rollers are of circularconformation in any section taken perpendicularly to the axis thereof,and each are of such maximum diameter that when in normal position withrespect to each of the corresponding pistons the rim 40 of the cammember 38 will be received between them with a desired minimum amount ofplay.

The rollers 60a are each so formed that the high point of its crownedsurface, that isthe point in the axial length of the roller which is ofgreatest diameter, is midway between the opposite ends thereof. In otherwords the high point of the crown is centrally disposed between theopposite ends of the rollers andfwhere the rollers are aligned with thecam surfaces 42 as illustrated, the rollers 68 will contact thiscorresponding surface 42 centrally of the width there-' of. On the otherhand, the high points of the crowns on the rollers 60b are dlsposednearest that side of the rollers 60b which is closest to the axis of theshaft I0 and, therefore, contact the corresponding cam surfaces 42 alonga circular line concentric -to but radially inwardly ofiset from theline of contact of the rollers 60a with the cam surfaces 42. The rollers600 in turn are arranged with the high points of their crowns adjacentthat end of the rollers more remote from the axis of the power shaft l0,and consequently these rollers contact the corresponding cam surfaces.42 along a line concentric with the line of contact between the rollers60a and the cam surfaces 42 but radially outwardly ofiset therefromhThus the rollers 60a, 60b and 600 contact the corresponding cam surfaces42 along circular lines of different radiion the cam faces 42, thusproviding three lines of contact between the rollers and theircorresponding cam surface on the same side of the cam member and servingto reduce the wear on the cam surface because of contact of the rollerstherewith by one-third as compared to the older construction. By thisrelatively simple modification of the older construction the useful lifeof the cam member may be increased to an extent to render its lifecommensurate with the life of other operating parts of the engine.

It might be noted that in'the construction illustrated in Figs. 5, 6 and'7 and as above described it is only necessary, when the rollers andpistons are suitably designed, to actually produce only two differenttypes of rollers as in such case the rollers 60b and 600 may beidentical with each other and simply reversed end-for-end from oneanother when assembled in their respective pistons.

It will, of course, be appreciated that for the purpose of illustrationthe amount of crowning of the rollers as shown in the drawings has beengreatly exaggerated, and that in actual practice the amount of crowningwill ordinarily be no greater than required to realize the purposes ofthe invention as described.

Formal changes may be made in the specific embodiment of the inventiondescribed without departing from the spirit or substance of the broadinvention, the scope of which is commensurate with the appended claims.

What I claim is:

1'. In an engine of the class wherein a group of cylinders are arrangedabout each end of a cably received by each opposed pair of cylinders,and an axial cam is fixed to the power shaft and is provided with curvedcam faces on axially opposite sides of the rim portion thereof forcooperative engagement with the pistons, the combination with saidpistons and cam of a roller rotatably carried by each of said pistons oneach side of said cam for engagement with the corresponding cam face ofsaid cam, said rollers having crowned peripheries, at least one of saidrollers contacting its corresponding cam surface at a different radialdistance from the axis of said power shaft than the point of contact ofanother of said rollers with the same cam face.

2. In an engine of the class wherein a group of cylinders are arrangedabout each end of a rotatable power shaft with their axes parallel tosaid shaft and each cylinder of each group is aligned with and opposedto a cylinder of the other group, a double ended piston is reciprocablyreceived by each opposed pair of cylinders, and an axial cam is fixed tothe power shaft and is provided with curved cam faces on axiallyopposite sides of the rim portion thereof for cooperative engagement.with the pistons, the combination with said pistons and cam of a rollerrotatably carried by each of said pistons on each side of said cam forengagement with the corresponding cam face of said cam, said rollershaving crowned peripheries, and at least one of said rollers beingformed with the high point of the crown thereof at a different axiallocation thereon with respect to the axis of said power shaft from thehigh point of the crown of another of said rollers on the same axialside of said cam.

3. In an engine of the class wherein a group of cylinders are arrangedabout each end of a rotatable power shaft with their axes parallel tosaid shaft and each cylinder of each group is aligned with and opposedto a cylinder of the other group, a double ended piston is reciprocablyreceived by each opposed pair of cylinders, and an axial cam is fixed tothe power shaft and is provided with curved cam faces on axiallyopposite sides of the rim portion thereof for cooperative engagementwith the pistons, the combination with said pistons and cam of a rollerrotatably carried by. each of said pistons on each side of said cam forengagement with the corresponding cam face of said cam, said rollersbeing of circular section in a plane perpendicular to the axis thereofand the diameters of said sections varying from one end of each saidroller to the other end thereof with the section of maximum diameterintermediate the ends of the rollers, the section of maximum diameter ofat least one roller being located at a distance from one end of saidroller different fromvthe distance which the section of maximum diameterof another roller on the same side of said cam is located with respectto the corre-' sponding end of such other roller.

4. In an engine of the class wherein a group of cylinders are arrangedabout each end of a rotatable power shaft with their axes parallel tosaid shaft andeach cylinder of each group is aligned with and opposed toa cylinder of the other group,'a double ended piston is recip rocablyreceived by each opposed pair of cylinders, and an axial cam is fixed tothe powershaft and is provided with curved cam faces on' axiallyopposite sides of the rim portion thereof for cooperative engagementwith the pistons, the combination with said pistons and cam of a rollerrotatably carried by each of said pistons on each side of said cam forengagement with the corresponding cam face of said cam, said rollershaving crowned peripheries, and the high point of the crown of one ofsaid rollers being located at a greater distance from the axis of saidpower shaft than the high point of another of said rollers on the sameside of said earn.

5. In an engine of the class wherein a group of cylinders are arrangedabout each end of a rotatable power shaft with their axes parallel tosaid shaft and each cylinder of each group is aligned with and opposedto a cylinder of the other group, a double ended piston is recipro cablyreceived by each opposed pair of cylinders, and an axial cam is fixed tothe power shaft and is provided with curved cam faces on axiallyopposite sides of the rim portion thereof for cooperative engagementwith the pistons, the combination with said pistons and cam of a rollerrotatably carried by each of said pistons on each side of said cam forengagement with the corresponding cam face of said cam, said rollers having crowned peripheries, and the rollers on each side of said cam beingarranged in groups, the rollers of one of said groups engaging thecorresponding of said cam faces along a line disposed at a greaterdistance from the axis of said power shaft than the line of contactbetween the rollers of another group and the same cam face.

6. In an engine of the class wherein a group of cylinders are arrangedabout each end of a rotatable power shaft with their axes parallel tosaid shaft and each cylinder of each group is aligned with and opposedto a cylinder of the other group, a double ended piston is reciprocablyreceived by each opposed pair of cylinders, and an axial cam is fixed tothe power shaft and is provided with curved cam faces on axiallyopposite sides of the rim portion thereof for cooperative engagementwith the pistons, the combination with said pistons and cam of a rollerrotatably carried by each of said pistons on each side of said cam forengagement with the corresponding, cam face of said cam, said rollershaving crowned peripheries, said rollers being so constructed andarranged in their respective pistons that the line of contact between aroller for one piston and its corresponding cam face is disposed at adifferent radial distance, measured from the axis of said power shaft,than the lines of contact between the corresponding rollers carried bythe said pistons next adjacent to said one piston and on angularlyopposite sides thereof, with said cam face.

7r In'an engine of the class wherein a group of cylinders are arrangedabout each end of a rotatable power shaft with their axes parallel tosaid shaft and each cylinder of each group is aligned with and opposedto a cylinder of the other group, a double ended piston is reciprocablyreceived by each opposed pair of cylinders, and an axial cam is fixed tothe power shaft and is provided with curved cam faces on axiallyoparranged in groups on each side of said cam member, a roller of onegroup being so constructed and arranged to contact the corresponding camface at a radial distance from the axis of said power shaft differentfrom the distance between the point of contact between the corre--sponding roller carried by the'next adjacent plstons angularly on eitherside of said piston, with said cam face.

KARL L.

